About this 3D model
The youtube video here https://www.youtube.com/watch?v=DBnKPEnt9a4 shows how to add flats to motor shafts that do not yet have them. Loosely based on the "Vise pad for holding 8mm threaded rod by ChatterComa" I created the part that helps you to grip the motor shaft properly in place so that you do not apply force to the motor inners.